feat: add .text-shadow-* utility class

source/_patterns/00-atoms/01-text/text-shadow.mustache

+<div>
+  <h1 class="head-alt-xl text-shadow-xs">{{ headline.short }}</h1>
+  <h1 class="head-alt-xl text-shadow-sm">{{ headline.short }}</h1>
+  <h1 class="head-alt-xl text-shadow">{{ headline.short }}</h1>
+  <h1 class="head-alt-xl text-shadow-md">{{ headline.short }}</h1>
+  <h1 class="head-alt-xl text-shadow-lg">{{ headline.short }}</h1>
+</div>

source/css/atoms/text-shadow.pcss

+@responsive {
+  .text-shadow-xs {
+    text-shadow: 1px 1px rgba(0, 0, 0, 0.2);
+  }
+  .text-shadow-sm {
+    text-shadow: 1px 1px .25rem rgba(0, 0, 0, 0.3)
+  }
+  .text-shadow {
+    text-shadow: 1px 1px .25rem rgba(0, 0, 0, 0.3);
+  }
+  .text-shadow-md {
+    text-shadow: 1px 1px .5rem rgba(0, 0, 0, 0.5);
+  }
+  .text-shadow-lg {
+    text-shadow: 1px 1px .5rem rgba(0, 0, 0, 0.8);
+  }
+}

source/css/style.pcss

@@ -36,6 +36,7 @@
 @import "./atoms/social-icon.pcss";
 @import "./atoms/super-button.pcss";
 @import "./atoms/table.pcss";
+@import "./atoms/text-shadow.pcss";
 @import "./atoms/tooltip.pcss";
 
 @import "./molecules/article-card.pcss";